wheres that smell coming from?

Bobbo wrote:

westend wrote:
Actually, a functioning air admittance valve may allow the trap water to be drawn out quicker when dumping as it allows for the displacement of the trap water.

I respectfully disagree. The one and only purpose of the AAV is to allow air into the drain line, without letting the air and smell back out, to prevent the suction that would pull the water out of the trap. The AAV doesn't accelerate the water draw, it prevents it.

You may disagree but physics is what it is. Think about this for a second. Take a piece of pipe and submerge it in water until there is water in the pipe. Place your hand over the end and withdraw the pipe. Now remove your hand. The water that was trapped in the pipe will then come out the bottom. Your AAV acts just like your hand in this example. If it is functioning, it allows air into the drain pipe when the water is flowing down the drain and closes at normal atmospheric pressure to block any air from coming back out.